The present invention relates to highly sensitive biological and chemical sensors, to a method for the detection of biological and chemical agents using such sensors and to a chemical moiety combination used in such sensors and in such detection methods. This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).
Biosensors are sensors that detect chemical species with high selectivity on the basis of molecular recognition rather than the physical properties of analytes. See, e.g., Advances in Biosensors, A. P. F. Turner, Ed. JAI Press, London, (1991). Many types of biosensing devices have been developed in recent years, including enzyme electrodes, optical immunosensors, ligand-receptor amperometers, and evanescent-wave probes.
The detection mechanism in such sensors can involve changes in properties such as conductivity, absorbance, luminescence, fluorescence and the like. Various sensors have relied upon a binding event directly between a target agent and a signaling agent to essentially turn off a property such as fluorescence and the like. The difficulties with present sensors often include the size of the signal event which can make actual detection of the signal difficult or affect the selectivity or make the sensor subject to false positive readings.
Amplification of fluorescence quenching has been reported in conjugated polymers. For example, Swager, Accounts Chem. Res., 1998, v. 31, pp. 201-207, describes an amplified quenching in a conjugated polymer compared to a small molecule repeat unit by methylviologen of 65; Zheng et al., J. Appl. Polymer Sci., 1998, v. 70, pp. 599-603, describe a Stern-Volmer quenching constant of about 1000 for poly(2-methoxy,5-(2xe2x80x2-ethylhexloxy)-p-phenylene-vinylene (MEH-PPV) by fullerenes; and, Russell et al., J. Am. Chem. Soc., 1982, v. 103, pp. 3219-3220, describe a Stern-Volmer quenching constant for a small molecule (stilbene) in micelles of about 2000 by methylviologen. Despite these successes, continued improvements in amplification of fluorescence quenching have been sought. Surprisingly, a KSV of greater than 105 has now been achieved.
It is an object of the present invention to provide a specific sensing system wherein the sensor can yield a distinctly recognizable signal event upon the binding of a target agent by a recognition element of the sensor.
It is a further object of the invention to provide a chemical moiety for use in a sensor system, the chemical moiety including a recognition element, a tethering element and a property-altering element.
To achieve the foregoing and other objects, and in accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention provides a sensor including a polymer capable of having an alterable measurable property from the group of luminescence and electrical conductivity, the polymer having an intermediate combination of a recognition element, a tethering element and a property-altering element bound thereto so as to alter the measurable property, the intermediate combination adapted for subsequent separation from the polymer upon exposure to an agent having an affinity for binding to the recognition element whereupon the separation of the intermediate combination from the polymer results in a detectable change in the alterable measurable property, and, a means of detecting said detectable change in the alterable measurable property.
The present invention further provides a method of detecting a biological agent including contacting a sample with a sensor including a polymer capable of having an alterable measurable property from the group of luminescence and electrical conductivity, the polymer having an intermediate combination of a recognition element, a tethering element and a property-altering element bound thereto so as to alter the measurable property, the intermediate combination adapted for separation from the polymer upon exposure to a biological agent having an affinity for binding to the recognition element whereupon the separation of the intermediate combination from the polymer results in a detectable change in the alterable measurable property; and, detecting said detectable change in the alterable measurable property.
The present invention still further provides a chemical moiety including a recognition element, tethering element and property-altering element bound together in combination wherein the recognition element is bound to the tethering element and the tethering element is bound to the property-altering element, the combination adapted for complexation with a polymer having an alterable measurable property selected from the group of luminescence and electrical conductivity.
The present invention still further provides a kit for the detection of biological agents, the kit including a fluorescent polymer and a chemical moiety including a recognition element, which binds to a target biological agent, and a property-altering element which fluoresces or changes fluorescence to a distinguishable degree bound together by a tethering element, said chemical moiety adapted for complexation with a fluorescent polymer, wherein, in the presence of binding of said recognition element to said target biological agent, the fluorescence emitted by said polymer is altered from that emitted when said binding between said recognition element and said target biological agent does not occur.